Rivers, floodplains & wetlands

Rivers, floodplains and wetlands may be affected by water management decisions. It is important to understand the impact of management actions on these ecosystems.

Rivers and streams

Our rivers are a source of water for many functions:

  • drinking and household needs
  • industry and agriculture
  • recreational use
  • fundamental environmental services.

The ecology of a river includes the fauna and flora and their physical habitats.

Information about the physical and chemical state of the water, the dynamics of water flow, the transport of nutrients, transformation by microorganisms and other microscopic animals and how that affects the flora and fauna is important to understand.

The health of a river depends on its capacity to support these key processes and life forms.

Across Australia our knowledge of how our rivers function is incomplete and the department is undertaking a number of studies to enhance our understanding of how these river ecosystems respond to droughts and changing river flows and water levels.

Such knowledge and information is essential to not only ensuring that our water resource planning adequately considers the rivers and their ecology, but also to ensuring that the way we manage catchments and land use considers potential off-site impacts and mitigates against any decline in river health.


A floodplain is an area of land next to a river that is subject to inundation during high rainfall or river flow periods. The soils are usually made up of sediments that have been deposited onto the plain from previous flooding. Some areas of floodplains remain wet after flood waters recede. These areas are called wetlands.

Floodplains are unique ecosystems that provide support for diverse ecological communities including many threatened species. They also provide food for aquatic animals such as fish and waterbirds.

Floodplain management decisions need to consider cultural, social and economic needs of the community as well as the natural ecosystems that it sustains.

The Office of Environment and Heritage consults with the Department to prepare rural floodplain management plans that define requirements for the management of floodwaters within floodplains.

Visit the NSW Office of Environment and Heritage for more information.

The department manages approval of controlled works on designated floodplains under Part 8 of the Water Act 1912.


Wetlands are important for supporting cultural, ecological, social and economic values and uses. These include Aboriginal meeting places, waterbird breeding, fishing and grazing.

Healthy wetlands manage nutrient and sediment inputs into oceans and rivers, mitigate floods, recharge groundwater and reduce soil erosion. They follow a pattern of wetting and drying that stimulates growth and breeding of plants and animals.

When wet, wetlands serve as wildlife drought refuges. The drying phase allows plant decomposition, nutrient release and seed set. Re-flooding triggers prolific growth for plants, insects, fish, waterbirds and other animals including internationally significant migratory birds.

Without flooding plant seed banks and insect egg banks can die. Wetlands that are wet for too long can develop acid sulphate soils and increase the risk of heavy metal exposure.

Currently, wetlands support animals not native to Australia such as grazing cattle and sheep. Pest species such as pigs, goats, cats, deer, rabbits, foxes and European carp are also present in most NSW wetlands. When not managed properly these animals can cause loss of biodiversity and poor water quality.

Monitoring wetlands provides NSW Government with knowledge that is used to assess water sharing plans and improve management of water resources for the environment. This includes responding to climate change effects observed in wetlands of International, National and State significance such the Macquarie Marshes, Gwydir and Gingham wetlands, Murrumbidgee wetlands, the Great Cumbung Swamp and the Booligal Wetlands.